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What is the formal difference in Scala between braces and parentheses, and when should they be used?
...e method expects a single parameter. For example:
List(1, 2, 3).reduceLeft{_ + _} // valid, single Function2[Int,Int] parameter
List{1, 2, 3}.reduceLeft(_ + _) // invalid, A* vararg parameter
However, there’s more you need to know to better grasp these rules.
Increased compile checking with pare...
How to parse XML to R data frame
...ude start_valid_time hourly_temperature
1 29.81 -82.42 2013-06-19T16:00:00-04:00 91
2 29.81 -82.42 2013-06-19T17:00:00-04:00 90
3 29.81 -82.42 2013-06-19T18:00:00-04:00 89
4 29.81 -82.42 2013-06-19T19:00:00-04:00 ...
How to add a custom loglevel to Python's logging facility
... example that checks if the logging level is enabled:
import logging
DEBUG_LEVELV_NUM = 9
logging.addLevelName(DEBUG_LEVELV_NUM, "DEBUGV")
def debugv(self, message, *args, **kws):
if self.isEnabledFor(DEBUG_LEVELV_NUM):
# Yes, logger takes its '*args' as 'args'.
self._log(DEBUG...
How to clear the interpreter console?
...s file in your python search path:
# wiper.py
class Wipe(object):
def __repr__(self):
return '\n'*1000
wipe = Wipe()
Then you can do this from the interpreter all you like :)
>>> from wiper import wipe
>>> wipe
>>> wipe
>>> wipe
...
jsonify a SQLAlchemy result set in Flask [duplicate]
...u actually haven't executed your query. Try following:
return jsonify(json_list = qryresult.all())
[Edit]: Problem with jsonify is, that usually the objects cannot be jsonified automatically. Even Python's datetime fails ;)
What I have done in the past, is adding an extra property (like serializ...
pip broke. how to fix DistributionNotFound error?
...s problem in my MacBook, the reason is because as @Stephan said, I use easy_install to install pip, and the mixture of both py package manage tools led to the pkg_resources.DistributionNotFound problem.
The resolve is:
easy_install --upgrade pip
Remember: just use one of the above tools to manag...
What's the difference between echo, print, and print_r in PHP?
I use echo and print_r much, and almost never use print .
11 Answers
11
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What are the differences between the threading and multiprocessing modules?
...nd a thread pool like this:
with concurrent.futures.ThreadPoolExecutor(max_workers=4) as executor:
executor.submit(job, argument)
executor.map(some_function, collection_of_independent_things)
# ...
You can even get the results of those jobs and pass them on to further jobs, wait for t...
Empty set literal?
...>> print(s)
set()
this is basically a more condensed way of doing {_ for _ in ()}, but, don't do this.
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How to get current CPU and RAM usage in Python?
...#!/usr/bin/env python
import psutil
# gives a single float value
psutil.cpu_percent()
# gives an object with many fields
psutil.virtual_memory()
# you can convert that object to a dictionary
dict(psutil.virtual_memory()._asdict())
# you can have the percentage of used RAM
psutil.virtual_memory().pe...